A)x^2+x=0 x(x+1)=0 x=0 или x+1=0 x=-1
б)x^2-4x+3=0 D=(-4)^2-4*1*3=16-12=4 x1=(4+2)/2=6/2=3
x2=(4-2)/2=2/2=1
в) 5x^2+14x-3=0 D=14^2-4*5*(-3)=196+60=256=16^2
x1=(-14+16)/(2*5)=2/10=0,2 x2=(-14-16)/(2*5)=-30/10=-3
г)x^2-2x-2=0 D=(-2)^2-4*1*(-2)=4+8=12
x1=(2-
![\sqrt{12}](https://tex.z-dn.net/?f=+%5Csqrt%7B12%7D+)
)/2=(2-
![\sqrt{4*3}](https://tex.z-dn.net/?f=+%5Csqrt%7B4%2A3%7D+)
)/2=(2-2
![\sqrt{3}](https://tex.z-dn.net/?f=+%5Csqrt%7B3%7D+)
)/2=(2*(1-
![\sqrt{3}](https://tex.z-dn.net/?f=+%5Csqrt%7B3%7D+)
))/2=1-
![\sqrt{3}](https://tex.z-dn.net/?f=+%5Csqrt%7B3%7D+)
x2=(2+
![\sqrt{12}](https://tex.z-dn.net/?f=+%5Csqrt%7B12%7D+)
)/2=(2+
![\sqrt{4*3}](https://tex.z-dn.net/?f=+%5Csqrt%7B4%2A3%7D+)
)/2=(2+2
![\sqrt{3}](https://tex.z-dn.net/?f=+%5Csqrt%7B3%7D+)
)/2=(2*(1+
![\sqrt{3}](https://tex.z-dn.net/?f=+%5Csqrt%7B3%7D+)
))/2=1+
![\sqrt{3}](https://tex.z-dn.net/?f=+%5Csqrt%7B3%7D+)
д)5x=3x^2 5x-3x^2=0 x(5-3x) x=0 или 5-3x=0 -3x=-5 x=5/3=1(2/3)
е)x^2-5x+4=0 D=(-5)^2-4*1*4=25-16=9 x1=(5+3)/2=8/2=4
x2=(5-3)/2=2/2=1
ж) 7x^2-4=0 7x^2=4 x^2=4/7 x=
![\sqrt{4/7}](https://tex.z-dn.net/?f=+%5Csqrt%7B4%2F7%7D+)
з) 3x^2-x+2=0 D=(-1)^2-4*3*2=1-24=-23 - корней нет
S=Vt => t=S/V
S=(V+2)(t-4)
S=(V+2)(S/V-4)
70=(V+2)(70/V-4)
70=70-4V+140/V-8
4V²+8V-140=0
V²+2V-35=0
D=1+35=36
V=-1+6=5
Ответ 5
С²-16с=с·(с-16)
с³-16с=с·(с³-16)=с·(с-4)·(с+4)
Объяснение:
3х²-3х+4х-4 ≤0
3х²+х-4≤0
3х²+х-4=0
Д=1-4*3*(-4)=1+48=49
х1=(-1+7)/6=1
х2=(-1-7)/6=-1 целых 1/3
рисуем параболу, ветки вверх
хЄ [-1 1/3; 1]